The present disclosure relates generally to circular knitting machines having needles and sinkers that cooperate to form stitch loops. The disclosure relates more particularly to circular knitting machines having sinkers whose movements are controlled by sinker cam segments that make up a sinker cam ring.
FIG. 1 depicts an example of two adjacent sinker cam segments 10, 20 making up part of a sinker cam ring in accordance with the state of the art existing prior to the present invention. The sinker cam segments 10, 20 define part of a sinker cam track 30 that is engaged by a portion (e.g., a butt) of each sinker. The sinkers are carried by the rotating cylinder of the machine, and the portions of the sinkers engaged in the cam track 30 move along the track as indicated by arrow A in FIG. 1. The sinker cam track 30 defines sinker cam surfaces 32 that control the inward (advancing) and outward (retracting) movements of the sinkers. More particularly, the sinker cam surfaces 32 include sinker-advancing surfaces 34 that cause the sinkers to be advanced radially inwardly, and sinker-retracting surfaces 36 that cause the sinkers to be retracted radially outwardly. As illustrated, it is common for the sinker cam ring to be formed of a plurality of sinker cam segments, two of which are shown in FIG. 1. Each of the sinker cam segments 10, 20 includes both a sinker-advancing surface 34 and a sinker-retracting surface 36. The joints or “breaks” between adjacent segments 10, 20 are located at the crests of the sinker cam surfaces 32. As a sinker travels along the cam track 30, the sinker must transition from one segment to the next, and thus must pass over the breaks between segments.